A large number of complexing agents for metal ions are used in a wide variety of applications, such as: semiconductor cleaning, detergents and cleaners, electroplating, water treatment and polymerizations, the photographic industry, the textile industry, the papermaking industry, pharmaceuticals, cosmetics, foodstuffs and plant feeding.
Semiconductor processing applications increasingly rely on chemistries containing complexing agents. There are more than one hundred steps in a standard IC manufacturing process that involves wafer cleaning or surface preparation, including post-resist strip/ash residue removal, native oxide removal, and even selective etching. Although dry processes continue to evolve and offer unique advantages for some applications, most cleaning/surface prep processes are “wet,” and have been found to benefit from the use of complexing agents in such wet compositions.
Moreover, such wet processes occasionally involve the use of chemicals that may present environmental challenges, such as hydrofluoric acid, hydrochloric acid, sulfuric acid, phosphoric acid or hydrogen peroxide. Due in part to environmental concerns, the use of more dilute chemistries has increased and has been aided by the use of some form of mechanical energy, such as megasonics or jet-spray processing. Accordingly, there is a need for chemistries that can be effectively used in diluted form.
Most formulations, being used in semiconductor applications, contain complexing agents or chelating agents. Metal chelating functionality is known in which a central metal ion is attached by coordination links to two or more nonmetal atoms (ligands) in the same molecule. Simple acidic organophosphorous chelating agents clean metals in aqueous solution essentially by a cation exchange reaction between the replaceable proton of the phosphonic acid OH group and the coordinating metal cation. Heterocyclic rings are formed as part of the coordination complex with the central (metal) atom as a member of each ring. When the complex becomes more soluble in the solution in which it is present, it functions as a cleaning process. If the metal complex is not soluble in the solution in which it is present, it becomes a passivating agent by forming an insoluble film on top of the metal surface.
Examples of complexing agents are nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), N,N′-bis(2-hydroxyphenyl) ethylenediiminodiacetic acid (HPED), triethylenetetranitrilohexaacetic acid (TTHA) desferriferrioxamin B,N,N′,N″-tris[2-(N-hydroxycarbonyl)ethyl]-1,3,5-benzenetricarboxamide (BAMTPH), ethylenediaminediorthohydroxyphenylacetic acid (EDDHA), ethylenediaminetetramethylenephosphonic acid (EDTMP), α-(hydroxyimino)phosphonic acid, propylenediaminetetraacetic acid (PDTA), hydroxypropylenediaminetetraacetic acid (HPDTA), isoserinediacetic acid (ISDA), β-alaninediacetic acid (β-ADA), hydroxyethanediphosphonic acid, diethylenetriaminetetraacetic acid, diethylenetriaminetetramethylenephosphonic acid, hydroxyethyleneaminodiacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, diethanolglycine, ethanolglycine, citric acid, glycolic acid, glyoxylic acid, acetic acid, lactic acid, phosphonic acid, glucoheptonic acid or tartaric acid, polyacrylates, carbonates, phosphonates, and gluconates, for example.
The complexing agents currently in commercial use, such as, glycolic acid, glyoxylic acid, lactic acid and phosphonic acid, are acidic in nature and have a tendency to attack the residue and remove both metals and metal oxides, such as, for example, copper and copper oxide. This undesired result presents a problem for formulators where a chelating function is sought only selectively to metal oxide residues and not to the metal itself, e.g., in an application involving metal, such as copper. Accordingly, there is a need for complexing agents that are not aggressive toward metal substrates, but still effectively chelate unwanted metal ion residues created during manufacturing processes.
U.S. Pat. Nos. 6,143,705, 6,310,019, 6,395,693, 6,410,494, 6,440,856, 6,514,352, 6,514,921, 6,534,458, 6,541,434, 6,716,803, 7,250,391, 7,312,186, and 7,541,322 discuss various compositions and methods of cleaning semiconductor substrates containing oximes, phosphonic acids, and organic acids. The compositions and methods of use are incorporated herein by reference in their entirety.
International Patent Application Nos. WO2009085072, WO2009058288, WO2009058278, WO2009058277, WO2009058275, WO2009058274, and WO2009058272 disclose a series of chelating agents with an amidoxime functional group. The cleaning compositions and methods of use are incorporated herein by reference in their entirety.
However, all these compositions require the use of, a combination of individual compounds with carboxylic functionality, amidoxime functionality and phosphonic functionality to achieve the desired cleaning performance as described in, for example, U.S. Pat. Nos. 6,395,693 and 6,541,434.
U.S. Pat. No. 7,427,361 describes the use of polymeric bounded chelator compounds, before being attached to the particle, and possesses at least three functional groups selected from the group consisting of hydroxyls, carboxylic acids, amines, amides, imines, imides, mercaptans, sulfonic acids, hydroxamic acids, carbonyl groups, esters, ethers, ureas, cyano groups, nitro groups, carbonates, inorganic salts thereof, and a combination thereof in a polishing slurry system. The polymeric system includes poly(styrene sulfonic acid), poly(vinyl sulfonic acid), poly(acrylic acid), poly(methacrylic acid), a poly(acrylate), a poly(methacrylate), a poly(alkacrylate), poly(maleic acid), poly(vinyl acetate), poly(vinyl alcohol), poly(acrylamide), poly(cyanoacrylate), a cellulosic material, and a combination or copolymer thereof. However, the different moieties are each separately attached to the polymer instead of being self-contained in the same molecule. Furthermore, the '361 patent does not include phosphonic and oxime moieties, which each provide unique synergistic effects with the carboxylic moiety. Moreso, the '361 patent fails to specify an arrangement of functional groups or the importance of arranging the moieties in a particular way attached to the polymer.
U.S. Pat. Nos. 7,527,733, 6,218,563, 5,948,931, 5,945,082, 5,935,542, 5,905,163, 5,861,525, 5,859,290, 5,859,278, and 5,858,317 describe the preparation of α-(Hydroxyimino) Phosphonoacetic acids and its chelating properties. U.S. Published Application No. 20060065604 describes the preparation of attaching α-(Hydroxyimino) Phosphonoacetic acids moiety to a macroporous polymeric system.
Troika acid is α-(hydroxyimino)phosphonoacetic acid or α,α-disubstituted trifunctional oximes which has a phosphonate, oxime and carboxylate moieties anchored to a common carbon atom in a single molecule. Due to the unique isomeric location of the oxime hydroxyl group, this group can interact via hydrogen-bonding with either of its two neighboring groups, depending on its orientation.

Troika acids have unique properties not found in other chelating agents used in the art. For example, the mode of chelation for the Troika acids is different from common chelating agents such as ethylenediaminetetraacetic acid (EDTA). Specifically, a ligand such as EDTA coordinates a metal ion directly through an amine nitrogen atom, whereas a Troika acid coordinates through an oxime nitrogen atom.
Additionally, by virtue of its unique central location in the Troika acid structure, the oxime OH group can hydrogen-bond with either of its two neighboring groups, giving rise to two isomeric configurations. The two isomers are based on the orientation of the N—OH in space. Each of the two isomers has different properties. Thus, the oxime hydroxyl group significantly influences, if not directs, the chemical reactivity of either of its two neighboring groups, depending upon its position.
Troika acids and their derivatives act as chelates by forming coordinate bonds between a pair of Troika acid heteroatoms and a metal cation. This means Troika acids can chelate to a metal cation through an oxygen on the phosphonate (acid or ester) group or a carboxylic acid oxygen atom and the oxime nitrogen atom depending on its isomeric position. In both of these modes, the configuration that comprises the metal cation, the two chelating atoms and the Troika acid backbone between them, is a 5-membered ring, which is a particularly stable arrangement. Which of the two chelating modes is favored may be altered by the pH and an appropriate derivatization of the Troika acid.

In general, however, a Troika acid preferentially chelates a metal ion through the phosphonate and oxime group, i.e. E-Isomeric configuration.
In juxtaposition, cleaning needs and goals have become more demanding. Increasingly, wafers are being processed with a single-wafer approach, as compared to a batch immersion or batch spray system. The single-wafer approach requires fast and effective chemical cleaning. Further, in wafer cleaning applications, particle removal may not be the main objective. Other goals become the focus, such as removing native oxide or photoresist residue after strip/ash. Accordingly, there is a need for chemistries that can be used in both single-wafer and batch processing, while addressing a variety of goals in the removal process.
The compositions and methods encompassed and exemplified herein address these problems.
The discussion of the background to the invention herein is included to explain the context of the invention, parts of which are intended to support the claims herein. Statements in the background are not admissions, including that any of the material referred to was published, known, or part of the common general knowledge at the priority date of any of the claims.
In addition, throughout the description and claims of the specification, use of the word “comprise” and variations thereof, such as “comprising” and “comprises”, is not intended to exclude other additives, components, or steps.